Heater and thermo control therefor



oct. 8, 1940. N, DERBY 2,216,809

HEATER AND THERMO CONTROL THEREFOR f Filed Aug. l0, 1937 2 Sheets-Sheet 2 lil lil 45 v M s lQ/ryQ/L 44 ATTORNEYS lParental Oct. 8, 1940 HEATER AND THERMO CONTROL THERE FOR Norman L. Derby, Philadelphia, Pa.

Application August 10,

` 4 claims.

This invention lrelates to improvements in storage water heaters of the type which are heated by gas and to control means therefor.

In storage water heaters of this type as usual- 5r 1y constructed, the gases of combustion are mixed with free or secondary air at the burner and the hot gases then pass by natural draft in contact with the walls of the water container to heat the water therein to the required temperature. It is well known that gases of combustion having mixed therewith a minimum of outside air have a far greater heat carrying capacity at elevated temperatures than when mixed with an excess of outside or secondary air. It is also known that if cool gases of combustion are mixed with hot gases of combustion as they pass from the gas burner and the mixture thus produced is passed by forced circulation in contact with the walls of the water container, the heating effect im,` and the eiiiciency of the heater will be far greater than if the same volume of fuel is burned with an excess of air 'and is passed by natural draft in contact with the walls of the container.

Furthermore, the recovery, thatv is, the time necessary to heat a -given volume of water through ya certain range of temperatures is more rapid and efficient with forced circulation or recirculation than with the natural draft type of heater. 30 Most types of storage water heaters using a natural draft circulation are equipped with control means including a thermo-responsive device actuated by;` the temperature of the water being heated to control the supply of fuel to the main 35 burner and another thermo-responsive device actuated by the temperature adjacent a pilot burner to cut off the supply of fuel to the main burner and to the pilot burner when the pilot flame is extinguished. Under natural 'operating conditions, the main gas burner goes on and off at frequent intervals, depending upon the amount ,of hot water consumed. The pilot flame, however, burns continuously to ignite the gas at the main gas burner. The foregoing control is 45 usually accomplished by providing two independent valves in the supply line to the heater, one of which is controlled by the thermo-responsive device under influence of temperature 4of the water in the container to control the quantity 50 of gas flowing to the main gas burner. The other thermostatic device responsive to the temperature adjacent to the pilot burner is arranged to automatically close the second valve, which is arranged between the first valve and the main burner, when the pilot burner is extinguished.

1937, serial 10.158,343

An important object of the present invention is to provide a water heater with an improved, simplified and efficient thermo-responsive device for controlling the delivery of fuel to the main burner 4of a storage water heater. A further important object is to provide a novel control device of this sort which includes only a single valve under the dual control of thermo-responsive means actuated by the heat of the Water in the container and thermo-responsive means 10 actuated by the heat adjacent a pilot flame or other source by which the iiow of fuel to the main burner and to the pilot flame is controlled.

Another object is to provide, in a control device of this sort, thermo-responsive means of 15 novel construction which is of relatively great sensitivity and which has a large increment of movement compared to elements of this sort heretofore used so that correspondingly large increments of movement of the closure elements of the gas valve can be effected with slight differences in temperature.

Another object of this invention is to provide a storagewater heater of improved construction, in which the maximum efficiency and quick heating of the water may be had with a minimum consumption of fuel; also to construct a water heater of this type in which a minimum amount of free or secondary air is admitted to the burner, and in which cool gases of combustion are mixed and circulated with hot gases of combustion as they leave the burner. Another object is to provide, in a heater of this sort, means for eecting a forced circulation of the gases of combustion, and also to effect a forced mixing of cool and hot gases of combustion in a manner to cause a rapid passage of vsuch mixed l gases against the walls of the water container. A further object of this invention is to provide means for automatically controlling the circula" 40 tion and recirculation of the gases of combustion c and to automatically stop circulation thereof when the main burner is extinguished; also to provide means whereby the rate of circulation and the amount of fuel consumption may be controlled to vary the temperatures to which the Water may be heated, and to hasten the speed of recovery of the heater.

Other objects and advantages of the invention will appear in connection with the following description and claims.

In the drawings:

Fig. l is a vertical section of a storage type -water heater embodying the several improvements in accordance with my invention.

Figs. 2 and 3 are vertical sections of a manually operable valve for controlling the passage of gas to the pilot burner -of the heater.

Fig. 4 is an enlarged, fragmentary vertical section showing in detail the unitary assembly of my improved valve and control means for controlling the supply of fuel to the main and pilot burners of a water heater.

Fig. 5 is a horizontal section thereof, on line 5-5, Fig. 4.

Fig. 6 is a face view of the combined thermoresponsive element and switch for controlling the circulating means for the gases of combustion formed in the heater.

In the embodiment of the invention illustrated. see Fig. 1, my improved storage water heater comprises an upright tank or container I which may -be formed of sheet metal having a cylindrical upright wall II, a top wall I2 and a bottom wall I3, all forming a water-tight receptacle. Water or other fluid to be heated may be introducted finto the container III through a pipe I4 near the lower end of the container and withdrawn through a pipe I near the upper endv of the container.

As shown, the container III is surrounded by a substantially air-tight housing having a cylindrical upright wall I6, a top wall I1 and a bottom wall I8. The wall I8 is disposed at a distance above the bottom margin of the wall I5, which preferably rests directly on the floor or other support for the heater. The housing described is disposed in spaced relation to the walls of the container I0 so as to form a narrow or confined space about the sides of the heater I0 which communicates with top and bottom narrow spaces 2i and 22 respectively. The housing is preferably provided with an insulating jacket 24 formed of asbestos plaster or other suitable material adapted to prevent the loss of heat through the walls of the housing.

Within the lower'part of the housing, below the bottom wall I8, is arranged a main gas burner 25 which is supplied with gas or other fuel by a pipe 26 which extends horizontally from the burner to the outside of the housing and then passes upwardly alongside the housing, as

shown. 'I'he upper end of the pipe 26 is connected to the discharge end of a valve 28 which receives a supply of fuel from a supply pipe 29 which is connected to the opposite or inlet end of the valve casing.

I preferably secure the upper or discharge end of the burner 25 in a hole 38 formed centrally in a funnel-like, downwardly extending central part of a plate 3| which is secured to the bottom face of the wall I8 of the enclosure I5. By this arrangement, substantially all outside or secondary air is prevented from mixing with the gases as they ignite at the.top face 32 of the burner.

In accordance with 4this invention, the gas supply valve 28 is the only one used for supplying gas to the main burner 25 and in order t0 not only control the supply of fuel therethrough in response to the heat oi' the water in the container I0, but also in response to the heat from a pilot burner 34 disposed adjacent the main burner 25, I provide the valve 28 with a sleeve 35 arranged within the valve casing and which is open at both ends so as to form an inlet port or seat 36 and a discharge port or seat 31. 'I'he sleeve 35,. as shown, is so disposed that when both ports are uncovered. gas from the supply pipe 28 may pass freely through the sleeve to the pipe 28 and the burner 25, but when either of these aaiesoa ports is closed, the supply of fuel to the main burner is cut off.

The pilot burner 34 is disposed close to the main burner 25,- and adjacent a hole 38 in the wall 3| so that a small ame from the pilot burner may enter this opening and ignite the gaseous mixture at the top 32 of the main burner 25. The pilot burner 34 is mounted at the end of a small tube or pipe 48 which extends horizontally out of the lower end of the housing I6 and thence upwardly alongside the pipe 26Where it connects with a spring loaded plug valve 4I, shown in detail in Figs. 2 and 3. Two branch pipes 42 and 43 are connected to ports in the casing of the valve 4I. l 'I'he branch pipe 42 communicates with the interior of the casing of the valve 28 between the sleeve 35 and the supply pipe 29 while the branch pipe 43, see Fig. 5, connects with a passage formed in the valve 28 and which terminates at a hole in the sleeve 35 between the seats 36 and 31. 'I'he valve 4I is of a well known three-way plug type which is yieldingly held in a definite position by a spring (not shown). In normal operation of the heater, that is, when the main burner 25 is burning, the valve 4I is held by its spring in the position shown in Fig. 3 wherein the supply of gas to the pipe 4I) and the pilot burner 34 is delivered by way of the supply pipe 29, port 36, the aperture in the sleeve 35 and branch pipe 43. At this time the pipe 42 is cut off from the pipe 40 at the valve 4I, as shown in Fig. 3. The other position of the valve shown in Fig. 2 will be explained later in connection with the thermo-responsive safety control means operating under the influence of the heat of the pilot burner 34.

As shown in detail in Fig. 4, I arrange for cooperativeI relation with the inlet seat 36 of the valve 28, a disk, valve or closure element 45 which is automatically movable towards and from the seat 35, or into and out of engagement therewith. I arrange a similar valve or closure element 46 for similar cooperative relation with the other seat 31 of the valve 28, and which is moved by automatic action, as will be explained.

Inl a boss 50 on the upper end of the casing of the valve 28, I secure an apertured screw plug 5I which, at its upper end, receives an elbow or pipe fitting 52 which includes a horizontal open ended branch 53. Into this open end 53 I screw the open, threaded end of a'tubular member or shell 54, which is closed at its opposite end and projects through the wall I6 of the housing and the adjacent side wall II of the water container I8 so as to extend into the water in the container. Within the threaded outer end of the tube or shell 54, I fix a transverse disk 55 having a central aperture 56 therein through which passes, in axial relation to the tube 54, a long slender rod 51. The inner end of the rod 51 has a screw-threaded, adjustable connection in a sleeve or tting 58 disposed in and spacedfrom the inner closed end of the shell 54. Upon this sleeve 58 at diametrically opposite sides of the rod 51, I secure the inner ends of a pair of reversed bimetal thermo-responsive strips or elements 60 of the form shown in Fig. 4. These elements may be constructed in accordance with the construction of such elements, as are disclosed in my Patent No. 2,086,857, Method of making bimetallic elements, to which reference may be had for further details. The stripsv 80 arerof like construction and are bent alternately in opposite directions, and are symmetrically disposed so as to be connected at inasiduos formed of high expansion metal having a positive rate of heat expansion so as to increase in length with an increase in temperature. The oppositely disposed strips 58 form together a thermoresponsive element having a negative rate of expansion, that is, a decrease in length with an increase in temperature as the result of an increase in curvature of the bends thereof. This arrangement of the positive and negative thermalthe rod in an opposite direction is equal to the contraction in length of this rod 51 plus the increase in length of the strips 50 upon a decrease in temperature.

The construction of thethermo-responsive device just described is very eiilcient in operation and has the ability to impart relatively large increments of movement to any device to which it is attached, with only slight variations in the temperatures to which it may be subjected.

Any suitable operative connection may be provided between the free end 52 of the rod 51 and the outlet closure element 45 oi the valve 28 for controlling the passage of fuel from the valve to the main burner 25 by way of the port 31. That shown in the drawings, consists of a vertical stem 55 formed on the closure element 45 and extending upwardly through the aperture inthe plug I beforeI mentioned where its free, upper end is provided with a collar or shoulder 55. 'I'his collar bears upon the upper face of a laterally extending arm of a lever 51, while the other arm 58 of the lever extends upwardly and has its free end pivotally connected to the free end 52 of the rod 5 1. The free end of the lateral arm of the lever 61 is pivoted at 59 on the plug 5|, orother stationary part of the device.

Between the apertured portion of the plug 5| and the closure dislr 45, the stem 55 passes through and is secured to a thin metal plate or corrugated diaphragm, orv movable element 18, and between this element 19 and the adjacent face of the plug 5| is arranged an expansion spring 1I.

The operation of this form of connection between the rod 51 and the closure element 45 is such that the spring 1I, acting upon the diaphragm 18, tends to move the closure element 45 into engagement with the seat 81, while the engagement of the lateral arm of the lever 51 against the collar 55 of the valve stem acts to lift the closure element 45 upwardly into open position against the action of the spring 1| to varying extents, according to the movement of the free end 52 of the rod 51 to the right or left under the iniiuence of variations in temperatures of the water in the container I8, as explained.

In addition to this controlled Iactuation of the closure member 45, an additional adjusted control may be provided by varying the relative position of the rod 51 with regard to the elements 58. This may be eiected in any suitable way,

as by a lever 15, fixed upon thefree end of the rod 52 and extending radially therefrom outwardly through a slot in the horizontal part 53 of the fitting 52 and which, by swinging the lever or arm 15 in an upward or downward i"di-- rection, will cause the rod 51 to move lengthwise in one direction or another by means of its threaded connectionwith the sleeve 58, the direction of movement depending on the direction of movement of the lever 15. This action will result in changing the position of the lever 51,

stem 55 and closure element 46 relative to the seat 31. The amount of adjustment may be indicated ,or set by a pointer 19 on the outer -end of the arm or lever 15 which cooperates with a suitable scale 85 on the outside of the part 53.

The means responsive to temperature at the pilot burner 34 or equivalent heat source for controlling the actuation of the other closure element 45 includes a depending vtube or shell 9|, which is secured at its upper open end to an apertured plug. 82 secured in an annular projection 83 extending downwardly from the casing of the valve 28. The lower end of the shell 8l is closed except for a small central aperture 88 therein. A thin walled tube 84, closed at its upper end projects into the shell 8| through the aperture 83, being secured in place by a suitable fitting 85 cooperating with the aperture. The tube 83 extends downwardly from the shell 8l to the lower portion of the heater where it is bent so as to extend through a hole in the side wall i5 ofthe housing from whence it extends to and terminates at a point adjacent to the pilot burner 34 in a closed end portion 84. Thus the closed end 84 of the tube is under the influence of heat from a ilame projecting towards the tube 8| from the pilot burner, see Fig. 1. This tube 83 is vacuum sealed and contains a small quantity of water orother vaporizable fluid, the vapor from which rises to the upper closed end of the tube.

To the plug 85 is fastened the lower ends of a pair of thermo-responsive, reversed bimetal strips oreiements 81 similar in construction and in action to the reversed bimetal thermal elements 50 before described. These strips 81 extend upwardly within the shell 8| and terminate near its upper end, and are connected atv intervals by apertured bridge pieces, through which the upper endof the closed tube 84 is guided. The free ends of the strips 81 are fastened to a part 88 at the lower end of a rod.89 axially arranged upon and depending from the inlet closure element 45 of the valve 28. This rod 89 passes through the aperture in the plug 82 and between the plug and closure element 45 is secured to a diaphragm 90 between which and the adjacent face of the plug an expansion spring 9| is arranged.l The spring 9|, as in the case of the spring 1I, acts to move the adjacent closure member ,towards its seat in opposition to the variable action imparted to the rod 89 by the -thermo-responsive device to which it is attached.

In this particular thermo-active device, the outer shell 8| is the positive element of the structure and expands lengthwise, or downwardly relatively to the valve 28 upon an increase-in temperature in the upper end of the tube v88,' whereas the strips 81 have a negative rate of heat expansion and decrease in length with an increase in temperature. A reverse action of the parts 8l and ,81 takes place upon a decrease in temperature.

The operation of this thermo-responsive device is such that when the pilot burner 34 is u' dit lighted and heat therefrom acts upon and vaporizes the liquid in the closed lower end 84 of the tube 83, the vapor which rises into the upper closed end of the tube 83 within the thermo- 'responsive device effects a transfer of heat to the device in varying degree such that in the presence of a normally high temperature from the vapor in the tube 83, the shell 8| will expand lengthwise in a downward direction, as stated. The negative elements 81 will, at the same time, contract under the influence of the heat from the tube 84, and since the lower ends of the elements 81 are fixed relatively to and move with the lower end of the tube 8|, movement is transmitted to the closure member 45 in an amount equal to the expansion of the element 8| plus the contraction of the elements 81 and in a direction to maintain the closure member 45 in open or spaced relation to its seat 36. This condition obtains as long 'as the pilot burner 34 is ignited. The'operation of the heater as thus far described isv as follows: Assuming that the main burner and the pilot burner 34 are both lighted, the' closure element 46 for the outlet se'at'31 ofthe valve 28 will be maintained in open relation to` the :seat and will be moved toward and from the same in accordance with variations in temperature of the hot water in the upper part of "the container `|0. The temperature of the rwate'r, of course, will vary in accordance with the extent and the frequency with which water is withdrawn from the container, and when the temperature of the'water in the upper part of thefcontainer reaches a predetermined degree, the closure element 46 will engage and close the seat 31 bythe action of the thermo-responsive device connected with the element 46, thus shutting off the supply of gas to the main burner 25.

-The other closure element 45 which controls the passage of gas into the sleeve 35 by way of the inlet port 36 is maintained in open relation to Ithe seat 36 as long as the pilot 34 is burning and effecting vaporization of the liquid contained 45 in the tube 83, the vapor from which will rise to "the upper end of this tubeand transfer its heat to and operate the thermostatic device comprising the shell 8| and strips 81. Therefore, as long as the pilot light is burning, the inlet seat 36 of the valve 28 will remain uncovered, and fuel will pass from the supply pipe 29 through both seats 36 and 31 in the valve sleeve 35 and the pipe 26 to the main burner 25, and by way of sleeve 35, branch pipe 42, valve 4| and pipe 40 l to the pilot burner 34. The amount of gas delivered tothe burner 25 will vary in accordance with the demand required to maintain the water at the desired temperature,` as explained, by movement of the closure element 46 toward and m from'the seat 31. Under operating conditions,

when, the desired temperature of the water in the upper part of the container has been reached, thethermostatic device controlling the closure member 46 will operate to close this member against the seat 31 of the valve 28 and cut off delivery of fuel to the main burner until such,

where it will at once be ignited by the pilot burner to again raise the water to the desired temperature.

During such operation of the heater, the supply of gas to the pilot burner 34 is continued by way of the pipe 29, sleeve 35, passage 43 and valve 4| to the pipe 40, as before explained, regardless of the intermittent closing of the seat 31. Passage of gas through the branch pipe 42 to the pipe 40 is prevented under these conditions by the position of the plug valve 4 If for any reason the pilot burner should be extinguished, the vaporization of the-liquid in the pipe 83 will cease, whereupon the shell 8| surrounding the upper end of said pipe 83 will contract lengthwise while the thermostatic strip elements 81 will extend in a lengthwise direction, and by the combined action of these two elements will cause the closure element to engage the inlet seat 36 and shut off the delivery of fuel, not only to the main burner 25 by way of the pipe 26, but also to the pilot burner by way of the sleeve 35 and passage 43, so that no fuel can now pass to the pilot burner until it is again lighted.

Thus, the thermostatic device composed of elements 8| and 81 acts in the nature of a remotely controlled safety device to positively prevent delivery of fuel to either burner should the pilot burner become extinguished for any reason.

In order to enable the pilot burner 34 to be relighted, the plug valve 4| must be turned through an angle of 90 to the position shown in Fig. 2, which will enable the fuel from the supply pipe 29 to be delivered to the pilot burner pipe 40 by way of the branch pipe 42 and valve 4|, while the branch pipe 43 remains cut off from the fuel supply by the seat closure member 45 and the plug of the valve 4|.

After the plug valve 4| has been turned to the position shown in Fig. 2, as above described, and-the pilot burner has been lighted, the valve is held in this position against the action of its spring until sufficient heat has been developed at the pilot burner to heat the fluid in the lower end 84 of the pipe B3. Generation of vapor which will rise to the upper end of the pipe will cause operation of the associated safety thermostatic device to shift the closure member 45 oi of the inlet seat so that fuel may-enter through the sleeve 35 and into the passage 43. By now releasing the plug valve 4|, its spring will return it to the position shown in Fig. 3, whereupon the fuel which is now enabled to enter the branch pipe 43 through the sleeve 35 will pass to the pipe 40 by way of the valve 4|, thus renewing normal automatic operation of the main burner and pilot burner under the control of the unitary fuel supply valve 28 and its associated thermostatic elements, as before explained.

' As previously stated. in storage Water heaters ofV this type, the usual procedure has heretofore been to cause the gases of combustion from the burner to rise by natural draft upwardly around the outside wall of the container I and then pass from the heater.

In accordance with the present invention, I provide a water heater construction whereby the gases of combustion, with the addition of almost no secondary air, are passed under forced draft or circulation quickly over the walls of the container, and I also further provide means whereby a portion of the gases of combustion, after passing over the walls of the water container and becoming cooled by such action, are mixed with and recirculated with freshly rising hot gases of combustion as they leave the burner.

For this purpose, I form in the heater construction illustrated, a column or passage |00 `which extends upwardly from the burner 25 and tainer I0, and the upper end |0| of said passage preferably terminat approximately midway between the upper and lower ends of said container.

The lower end of the column |00 terminates at the bottom wall I0 of the enclosure and registers with the opening of the part 3|, and in turn is closed by the burner 25.

Surrounding and disposed in spaced relation to the column or passage |00 is an upright annular duct |02 which communicates at its lower end with the space 22 before mentioned, between the bottom wall I3 of the container and the bottom wall l0 of the outer housing. 'I'he upper end of the duct |02 terminates in the upper space 2| between the top wall |2 of the container and the upper wall |1 of the housing, so that the upper and lower ends of the duct |02 yare in communi cation with the annular space 20 surrounding the container l0 between the wall and the housing. I alsopreferably arrange in the duct |02 adjacent and in spaced relation to the upper end |0| of the passage |00, a defiector |05 which has a central, depending more or less conical projection |06 terminating at or just within the upper end |0| of the passage |00. Surrounding the central portion |06 of the deilector |05 is an annular, downwardly facing concave space or passage |00, the lower outside edge of which is defined by the margin |09 of the deflector, as shown. 'Ihe deilector |05 is also provided with a central upstanding substantially conical part |I0, the side walls of which are arranged in spaced relation to the walls of the duct |02 which are preferably curved as shownadjacent the deflector for this purpose. upwardly in the column or passage |00 will, as they arrive at the open upper end |0| thereof, be diverted into the annular concaved passage |00, and as they impinge against the inner walls thereof, win be deflected downwardly thereby 1n a direction towards the lower portion of the duct |02.

Should the heater as thus described be operated under natural draft conditions, most, if not all of the gases of combustion entering the central part of the duct |02in the manner just described, would pass upwardly into the space between the deiiector |05 and the adjacent sides of the duct |02 and out of the upper end of the latter into the space 2|. I have shown in Fig. 1, two relatively small outlet pipes or openings I2 disposed in the top wall |1 of the housing I6 so as to permit a limited escape of the products of combustion from the heater. However, it is desirable, in order to effect the maximum emciency in this heater, to provide means for causing the gases of combustion, after leaving the upper end of the passage |00, to pass downwardly in the duct |02 to the space 22 and thence upwardly in the space 20 about and in contact with the outside walls of the container, so that heat from the products of combustion will heat the water not only through the walls 'of the duct |02, but also through the outside wall of the container. For this purpose, I provide means for causing this downward movement of the gases of combus- Thus, it Awill be seen `that gases rising' tion, preferably at a rate of speed in excess of normal draft conditions, the means shown in the drawings comprising a fan or other impelling device ||3 which is disposed in or adjacent the upper, open flaring end of the duct |02, as shown in Fig. 1. This fan or impeller may be mounted on a shaft which extends downwardly through the topwall of the outer housing of the heater and is operatively secured to an electric motor or the like driving unit ||4 mounted upon the top of the heater, as shown. The motor circuit includes a pair of conductors ||5 and H6, one' of which leads to a movable switch member cooperating with contacts IIB and ||9 for opening and closing the circuit in the usual manner. The other conductor ||5 extends into the space Within the lower portion of the housing and there makes'contact with a reversed bimetal thermoresponsive element |20 whichis preferably of substantially circular or ring-like formation, as shown in Fig. 6, and which may be constructed in accordance with the disclosure in my Patent No.' 2,086,857, before referred to. This thermoresponsive element. |20 has one of its sides secured in a bracket `|2| in fixed relation to or upon an adjacent part of the heater while at the diametrically opposite side of the device |20 to the bracket |2|, the device |20 is provided with a contact member |22. This contact |22 is arrange to engage a contact |23 'supported upon a fixed bar |24 suitably mounted upon and insulated from the housing I6, see Fig. 1. Extending from the contact |23 is a conductor |25 which connects with the supply line |26 from the source of electric current. The other supply line |21 is connected to the contact I9 for the switch member H1, preferably through an interposed rheostat or other variable resistance device |30, as

, shown in Fig. 1.

'I'he thermoresponsive element |20 is so coni structed that `it will, under the influence of heat, be distended or deformed in a vertical direction out of its circular form into a more or less elliptical formation, as indicated in Fig.l1, and` when in this condition, it will carry its contact |22 into engagement with the fixed `contact |23 to complete the circuit to the motor through the connections just described. r y

Accordingly, I mount the element |20 adjacent the main burner |25, as shown in Fig. 1, so that when said burner is ignited, heat therefrom will cause the motor circuit to be closed andthe motor jlnllaced in operation to rotate the fan or impeller Under these operative conditions, the fan ||3 will draw a considerable portion `of the relatively cool gases of combustion from the space 20 through the space 2| and force it downwardly through the upright duct |02 where, as it passes over the upper diverting face of the deiiector |05. it will mix with -the freshly produced heated gases of combustion rising from the burner through the passage |00 as these gases are discharged into the duct |02. The construction of the deilector and associated parts of the passage |00 `and the duct |02 is'such that an intimate mixture of the cool and hot gases will take place and the mixed gases will be forced downwardly through the duct |02 along the inside wallsof the container I0 across the bottom wall I3 thereof, and hence upwardly along the outside wall of the container I0, as long as the fan ||3 is operating.

Preferably, I arrange adjacent the inner ends of the openings |-|2, defiectors |32 which are so formed and positioned that they aid in directing the gases ascending upwardly in the space 20, largely towards the center of the heater, where they will be carried downwardly into the duct |02 to be mixed with the rising gases of combustion as they leave the passage |00, as explained.

As a result of thefnovel construction and arrangement of the parts of the heater as just de,- scribed, the streams of hot and cool gases of combustionflow smoothly together and mix below the deiiector |05 without building up an opposing pressure. The velocity of the cool gases passing the deector and the action of the fan is such as to cause an upward suction in the passage |00 to draw a large combustible charge into the burner 25.

The mixed cool and hot gases forced downwardly through the lowery portion of the conduit |02 and upwardly through the outer space 28, give up their heat to the inner and outer walls of the Water container. A portion of the mixed coo] gases passes to the open a at the outer lside of the defiectors |32 and the o lets ||2, the remainder of these gases being drawn by the fan or impeller into the duct |02 where they are forced downwardly again and mixed with the new hot gases below the deflector. 'I'his mixture resulting from the passage of these gases into the lower portion of the duct |02 where they mix with the hot gases arising from the passage |00 is recirculated, as before stated. The defiectors |32 are' so designed that while permitting a portionof the circulating and recirculating gases to pass into the open air, no outside air may enter the heater through the passages ||2, since the static pressure in the duct |02 and in the upper and lower connecting spaces 20 and 22 is such as to prevent the outside air from entering the heater as long as the fan is in operation.

On the other hand, the relatively small area of the discharge passages ||2 is such that, when the burner 25 is extinguished and the fan is stopped, very little outside air will pass into the heater by natural draft, so thatl the standby efficiency of the heater will be affected but little under these conditions.

The suction in the passage |00 may be regulated by regulating the speed of the circulating gases, which in turn is controlled by the speed of the motor ||4 and its associated fan ||3. Therefore, by moving the switch member from the contact ||9 into contact with one or another of the contacts of the rheostat |30, the

speed of the motor and, consequently the speed of the fan ||3 and the movement of the gases through the heater, can be varied and controlled, if desired.

With the switch ||1 in closed position, either engaging with its contact H9 or one of the contacts of the rheostat |30, the fan ||3 will be in operation as long as the main burner 25 remains ignited, since the heat from this burner actuating the thermostatic element |20, as explained, will cause the contacts |22 and |23 to be held in engagement to maintain the motor circuit in closed position. However, should the main gas burner 25 become extinguishedA for any reason, the removal of heat from the vicinity of the element |20 will cause the latter to resume its circular formation and thereby move its contact |22 out of engagement with the contact |23, thus opening the motor circuit and stopping the fan I have shown in Fig. 1 a trap |40 which comprises a pipe having reverse bends and which has one of its ends secured in the bottom wall I8 of the housing and in communication with the space 22 of the housing. This trap is water sealed and acts to relieve the spaces between the housing, the central duct |02 and the walls oi' the water f container of any water of condensation that may accumulate, as the burning gases always contain water vapor as a product of combustion.

I preferably provide the upper portion of the water container I0 with suitable heat insulation to prevent the hottest water at the top of the container from giving up heat to the cool circulating gases in the upper end of the duct |20 and in the spaces 20 and 2|. Any suitable means may be provided for accomplishing this result, such as the provision of a layer of aluminum or similar thin sheet metal or foil |4| arranged between the outside surface of the upper portion of the container I0 and an outer contacting layer of metal as indicated at |42.

The upper portion ofthe duct |02 is similarly insulated by a layer of foil |43 and a contacting sheet metal wall |44, while the walls of the passage |00 and the lower wall |8 of the housing to which it connects are similarly insulated as shown in Fig. 1.

The tube heater 83 containing the volatile liquid for heating the safety thermostat from heat at the pilot burner 34 may be insulated with an asbestos or the like covering (not shown), or may be coated with aluminum paint, with the excep tion of the generator end 84 and the upper end within the safety thermostatic device.

I preferably form in the shell 8| of the safety thermostatic device a plurality of small holes for the circulation of air therethrough. This will help the heating action of the tube 83 and cause a more rapid cooling of the thermoresponsive members 8| and 87 with consequent quicker closing action of the closure element 45, in the event that the pilot burner is extinguished.

Preferably, I form the sleeve member 35 of the valve 28 of some suitable permanently magnetic material, such for example as that known in the trade as Alnco, while the closure members 45 and 46 are preferably formed of a paramagnetic material such as 50% nickel steel, which is attracted by the permanent magnetic sleeve so asto effect quick opening and closing action of the closure elements when such movements thereof are initiated by theirrespective thermostatic devices.

Preferably, though not necessarily, I also provide in the contact members |22 and |23 which are associated with the thermoresponsive device |20 at the lower part of the heater, small permanent magnets of "Alnico" or the like, which are embedded in the contacts and operate to assist in effecting quick action between the contacts |22 and |23.

The improved heater above described is well adapted to reduce heat losses to a minimum by preventing excess outside air from entering at the base around the main burner so that no cool air may pass in contact with and carry heat from the water container by natural draft when the heater is in the standby condition, that is, with the burner 25 extinguished during which time hot gases are being generated only by the pilot a "L l andthe condensate will pass from the heater or some'other material that is not attacked by the highly corrosive acids dissolved in the condensate.

While I have shown and described my invention in connection with a domestic water heater, the application of the invention is not limited to such structuressince the same may be employed in connection with many other forms or types of water heaters or systems.

It will be understood that various changes in the details, materials and arrangements of parts, which have beenherein described and illustrated in order to explain the nature of my invention, may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended claims. For example, while I have shown and described the pilot flame as being produced by a separate pilot burner,`it should be obvious that the supply of fuel for the pilot flame could be delivered to the main burner gas pipe 2B and the main burner 25, with equally g'ood results. Also, if desired, I may substituteV forthe motor Ill, a two speed motor, that is, one having two independent windings with a switch to vary the speed of the fan II3. Such motors are well known, and it is deemed unnecessary to illustrate the same.

I claim:

1. 'I'he combination in a water heater having a water container, of a main fuel burner for heating the water therein, means for producing a pilot flame, and a pipe for supplying fuel to said main burner and pilot flame, of a single valve in said pipe having a casing, a sleeve therein formed of permanently magnetic material and having a seat at each end forming an inlet port and an outlet port respectively, closure .elements for each of said ports formed of paramagnetic material, a passage in said sleeve communicating with said pilot flame for conducting fuel from said valve to said pilot flame, a'thermostat responsive to the temperature of water in said container and operatively connected to said outlet closure element to regulate the flow of fuel to said main burner, and a second thermostatoperatively connected to said inlet closure element and responsive to temperatures adjacent said pilot flame to control the flow of fuelthrough said inlet port and said passage to said pilot flame, and said connections between said thermostats and said inlet `and outlet closure elements including means for facilitating quick opening and closing of said valve ports under the cooperative magnetic influence of the materials of which said sleeve and closure elements are formed.

2. The combination in a water heater'having a water container, of a fuel burner for heating the water therein and a valve for supplying fuel thereto and including a closure member cooperating with a seat in said valve, of thermostatic means for actuating said closuremember under the influence of the temperature of the water in said container, said thermostatic means including athermo-active element having a positive rate of expansion with an increase in temperature, a second thermo-active element having a negative rate of expansion and comprising a pair of re.

versed bimetal strips formed to contract lengthwise with an increasein temperature, said strips y being joined at intervals and each connected at one end to an end of said 'positive element, and said strips being fixed at their opposite ends, said other end of said positive` element being operatively connected to said closure member for moving the same towards and from said valve seat in response to changes in the temperature of the water, the movementv of the free end of said positive thermo-active element being equal to the increase in length of said positive element plus the decrease in length of said negative element and vice versa.

3. 'I'he combination in a water heater having aV water container, of a main fuel burner for heating the water therein, a pilot burner adjacent said main burner and a pipe for supplying fuel to both burners, of a single valve in said pipe having an -inlet port and an outlet port, a closure element for each port operable to independently open and close its port, thermostatic means operatively connected to one of said closure elements and which is responsive to the temperature of the water in said container to regulate the flow of fuel through said outlet port to the main burner, and other thermostatic means disposed at a point remote from said pilot burner, said thermostatic means including av thermo-active element having a positive rate of expansion with an increase in temperature, and which is fixed at one end, a second thermo-active element having duit closed at both ends and containing a vapor- I izable liquid, one end of said conduit being disposed adjacent said pilot burner so that heat therefrom may vaporize said liquid and the other end of said conduit being associated with said second thermostatic means so that the same will be affected by the presence of vapor in that end of said conduit to move said closure member towards and from said inlet port to control theflow of fluid therethrough to said outlet port, and the movement of the free end of said negative Yelement being equal to the increase in length of said positive element and the decrease in length of said negative element and vice' versa.

4. The combination in a. water heater having av shell which contains the water, of a burner for heating the water, valve means for delivering fuel to said burner, thermo-responsive means actuated by the temperature of the water for controlling the supply of fuel through said valve to said burner and for automatically cutting oif the supply of fuel thereto when a predetermined high temperature of the water is reached, whereby said burner is intermittently-extinguished and for again automatically effecting delivery of fuel through said valve to said burner when said water temperature is lowered, a pilot for igniting the fuel delivered to said burner, means for effecting forced circulation of the products of combustion from said burner into intimate contact with the walls of said shell including a motor driven fan, a switch and a thermostatic device, the latter being positioned so that, when products of combustion are being produced at said burner in accordance with the delivery of fuel thereto under the :action of said other thermo-responsive means, 'said thermostatic device will be influenced by the f 6 heat from said products of combustion to effect :closing of said switch and the operation of said fan, and, when said thermo-responsive means op- NORMAN L. DERBY. 

